1. Field of the Invention
The present invention relates to a method of writing hardware performance information of a unit incorporated in a vehicle. Particularly, the present invention relates to a method of writing hardware performance information for a control device of a unit.
2. Description of the Background Art
In the field of vehicle manufacturing, there is employed a production system of manufacturing a plurality of units constituting a vehicle at a plurality of different factories directed to each unit, and then assembling respective completed units together at a vehicle factory to form a unitary vehicle.
For example, an electronic control type transmission incorporated in a vehicle includes an automatic transmission main body and an electronic control device, each manufactured at different unit factories. The automatic transmission main body and the electronic control device delivered from respective factories are assembled at the vehicle factory, whereby a product of the electronic control type transmission is completed.
The automatic transmission main body includes electric components such as a plurality of solenoids and sensors for gear control and oil pressure control. Each automatic transmission main body has individual specificity, and the electric components exhibit some variation in the output property reflecting configuration variation generated during the manufacturing stage.
If the automatic transmission main body and electronic control device are assembled at random at the vehicle factory, deviation of the output property of the corresponding automatic transmission main body from the standard value, if any, cannot be corrected by the electronic control device, resulting in the additional increase of variation in the gear performance of the automatic transmission as a whole.
The need arises for an electronic control device to correct the control procedure based on the hardware performance information unique to each automatic transmission main body in various control operations in order to suppress variation in the transmission performance between automatic transmissions. Japanese Patent Laying-Open No. 05-215206, for example, discloses one such means.
FIG. 5 is a schematic diagram to describe an electronic control type transmission disclosed in the aforementioned publication.
Referring to FIG. 5, an electronic control type transmission includes an automatic transmission main body 60, and an electronic control device 70 installed at a site distant from automatic transmission main body 60.
Automatic transmission main body 60 includes a plurality of solenoids 62 for gear control and oil pressure control, a plurality of sensors 64 such as a vehicle speed sensor and throttle opening sensor, and a characteristic storage device 66 storing the characteristics of these control components. Each of the plurality of solenoids 62, the plurality of sensors 64, and characteristic storage device 66 is connected to electronic control device 70.
Characteristic storage device 66 stores the characteristics of solenoid 62 and sensor 64. For example, the output oil pressure property having a variation of a predetermined width with respect to the duty ratio is stored for the solenoid directed to oil pressure control.
At the time of initiating gear control, electronic control device 70 reads in a signal from characteristic storage device 66. At this stage, electronic control device 70 corrects the duty ratio based on the level of deviation of the output oil pressure with respect to the standard value. Accordingly, the control effected in practice will correspond to a solenoid 62 based on characteristics within the range of the standard value, even if the characteristics of solenoid 62 vary.
According to the automatic transmission of FIG. 5, variation in the gear performance can be reduced in totality of the automatic transmission. However, the manufacturing cost will be increased since it is necessary to incorporate a characteristic storage device 66 for each automatic transmission main body 60.
There is proposed a method of storing the hardware performance information of automatic transmission main body 60 on the part of electronic control device 70, taking into account the cost perspective (for example, refer to Japanese Patent Laying-Open No. 2003-254418).
FIG. 6 is a schematic diagram to describe the method of storing hardware performance information for an automatic transmission disclosed in Japanese Patent Laying-Open No. 2003-254418.
Referring to FIG. 6, this method includes the step of conducting a characteristic test on each individual unit to obtain test data after inspection of a completed product of automatic transmission main body 60 (step S100).
The spring set load, piston stroke, and clutch μ are obtained based on the test data (step S101).
Further, respective constants for gear control are determined based on respective values obtained (step S102). Specifically, the spring height is determined based on the spring set load; the stroke distance is determined from the piston stroke; and the pitch is determined from clutch μ. The determined spring height, stroke distance, and pitch are displayed as characteristic identification marks based on different colors, bar code, signs and the like (step S103).
Then, a label 80 with a characteristic identification mark is produced (step S104). This label 80 is attached at an appropriate site of a corresponding automatic transmission main body 60 (step S105).
Although not depicted, a characteristic identification mark is also attached in a similar manner for the control valve. The service personnel views the label attached to automatic transmission main body 60 and the control valve to write the constants for oil pressure control and gear control corresponding to each characteristic identification mark into a storage circuit of the electronic control device (not shown). A label with a constant identification mark corresponding to the written constants is attached to the electronic control device.
Eventually, the control valve is assembled with automatic transmission main body 60. Electrical connection is established between the electronic control device and automatic transmission main body 60 to complete an automatic transmission product.
As an alternative means to store hardware performance information of automatic transmission main body 60 into electronic control device 70, the means for detecting the hardware performance information of automatic transmission main body and writing the data into electronic control device 70 at a vehicle factory is known.
Although the automatic transmission of FIG. 6 does not require a characteristic storage device to be provided for each automatic transmission main body 60, it is mandatory that label 80 with the characteristic identification mark maintains a predetermined quality over a long span starting from the manufacturing stage at the unit factory until the time of repair at the service factory. In other words, label 80 must be durable towards degradation over time such as being peeled off or scratched away. Furthermore, a site of attachment must be ensured so as to facilitate visibility.
Furthermore, in order to store the hardware performance information of automatic transmission main body 60, the information must be written into electronic control device 70 for each unit based on the characteristic identification mark on label 80 at the time of manufacturing or repairing the automatic transmission. Productivity was not necessarily high.
In general, automatic transmission main body 60 is shipped to the vehicle factory after being inspected at the unit factory. This means that inspection of automatic transmission main body 60 will be carried out redundantly at the vehicle factory in the case where detection of the hardware performance information of automatic transmission main body 60 is conducted at the vehicle factory. This is one cause of degrading the productivity.